Clamp



G. B. BOSCO Nov. 24, 1936.

CLAMP Filed April '7, 1934 2 Sheets-Sheet l Patented Nov 24, 1936 UNITED STATES OFFiQ 1 Claim.

provided with very powerful elements to effect its withdrawal from the masonry after the concrete has set. 7

As will also hereafter be seen, my clamp may be employed advantageously with cabinet making and other operations requiring a clamp, although it is much stronger and more powerful than is usually used with such work. The economy possible in producing my clamps and the small price at which they can be supplied, is the principal advantage in their extension to fields other than for use with spacers and tie rods for concrete forms.

As will hereafter be seen, my clamps will perform the double function of spacing the opposing walls of a form from each other as well as maintaining them in the desired spaced relation against the distorting weight of the cement and aggregates when they are placed in the forms and the rods may be bent without interfering with the turning up of the screws thereon so that the nuts will function with form walls which are at an oblique angle, or at an angle other than with the tie rods.

I have attained the foregoing objects by means of the structure illustrated in the accompanying drawings, in which- Fig. 1 is an elevation from the side of a complete clamp, the threaded clamp bar at one end being shown with its flat sides in horizontal position and at the other end with its flat sides in vertical position. v

Fig. 2 is an end elevation, to an enlarged scale, of the clamp shown in Fig. 1.

Fig. 3 is a fragmental perspective of a portion of a threaded ing disk.

Fig. 4 is a section of a form for casting a concrete retaining wall with my clamps associated therewith.

Fig. 5 is a detail, partially in section, to a much enlarged scale, of an assembly of tie rod and form end bar associated with a clampwall which constitutes my clamp, a spacer as well as a tie rod.

Fig. 6 is a section through the nut illustrating the form in which the core is made to permit the drawing thereof from the core box, and

Fig. 7 is a fragmental detail, to an enlarged scale, of the special thread form employed.

Similar reference characters refer to similar parts throughout the respective views.

It is not unusual, and, in fact, is fairly general which are threaded, as at 6, upon which threaded ends are screwed extensions long enough to project through the forms and having threads and nuts or other means for pulling them up against the forms so that the forms will sustain the considerable weight of thesoft concrete with which the forms are fille My invention relates specifically to the form of the end extensions and nuts co-operating therewith which permit me to produce these elements at a substantially smaller figure than they have heretofore been produced, and. which in use may be drawn out of the green concrete structure with the application of less force and which will permit the nut to clean and clear the thread of adhering concrete and rust much more readily.

Heretofore these end. extensions have been made from rods upon which have been cut threads or milled slots for co-operating with nuts or other instrumentalities for pulling and securing the rods. The cost of cutting threads or milling slots is very much greater than the cost of any other portion of the structure or its fabrication so that the resulting clamp has always been a relatively expensive article.

Instead of forming my extensions from rods I heat and drop forge a bar of rectangular section so that I provide on the end thereof a cylindrical or rather tapered portion 1 which is bored and tapped, as at 8, to receive the threaded end 6 of the central spacer bar 5. Upon a pair of the opposite sides of the bar are formed, by the drop forging operation, threads 9, while the faces of the bar "I between the threaded faces are left plain and Without threading. vI have found that threads can be thus produced by drop forging which require no machining after the drop forging operation, while complete circumferential threads cannot be so produced.

In order to render my clamps capable of performing the function of a spacer, as well as a tie rod, I bore an inclined hole 1a between the flat 2 faces in of the bar just back of the tapered portion I. The hole is of such size as to receive a nail lb which is driven through the bar into the form, as most clearly shown in Fig. 5. It is the present general custom to have the central rods or spacer bars 5 cut to specification and the above described arrangement permits the spacing of the opposing members of the form to be done from the outside of the form instead of from the inside of the form as is now the usual practice. The boring of the hole la is a comparatively easy operation between the flat faces ill-l of my rod. but the provision of such a transverse oblique hole in the round or cylindrical rod is difficult, uncertain and expensive.

It will be noted from an examination of Fig. '7 that the threads 9-4 formed on opposing edges of the rectangular bar are unusual in that the faces Illa. of the threads are curved in cross section and are merged in easy curves with curved bottoms or roots lilb between adjacent threads and curved tops llic. This would not be as effective a design for all varieties of screws as threads with flatter faces and squarer tops and bottoms, but the pitch of my screw is a half inch with ample metal in the thread so that it constitutes a powerful and effective thread easily made by a drop forging process.

To assemble with the threaded portions of the bar I provide a nut, one side i l whereof is flared or extended to provide an ample bearing upon the stringer or whaler I! of the form l3. Running diametrically across the nut back of its flared face or side is a rib H with lateral abutments I positioned to reinforce the rib when it is being forced in a clock-wise direction.

The difficulty in casting nuts with taps complete has heretofore largely lain in providing a core for the tap which could be drawn from the core box, as a true spiral will prevent the members of the core box from being separated without destroying the core. I have overcome this difliculty in the manner shown in Fig. 6 in which the ridges in the core box, which provide the grooves Ila in the nut, are slightly deflected from the true helix as they approach the plane upon which the members of the core box are separated so that the ridges llb in the nut are out of line and slightly displaced at the points where the members of the core box join. This permits the core to be formed and withdrawn from the core box and produces the nut with slightly off-set ridges, as shown in Fig. 6, which will easily cooperate with the threads 9-9 on the opposite sides of my clamp bar. The elimination of all machining operations in the production of these parts very greatly reduces the expense of their production.

A bend in a bar with complete circumferential threads will cause the nut to bind or stick at the bent portion, but the bar herein illustrated and described may be bent materially in the direction of the plane of the threads, or in the plane at right angles to the flat sides, without in any way interfering with the co-operation of the nuts therewith. Heretofore the stringers or Whalers l2 had to be blocked out, as shown in connection with the upper clamp in Fig. 4, to bring them at right angles to the tie rod but with my clamp no blocking out is necessary as the bending of the bar will not prevent the nut from co-operating with an oblique seat, as shown in the lower tie rod inFig. 4.

The forms are generally removed from the cast structure after the initial set of the cement but while the concrete is still what is called green" and not completely hard. The nuts may be screwed on the bar either by means of a wrench co-operating with the ribs H or by merely driving the ends of the webs around with a hammer. If it is desired to rotate the bar two nuts may be screwed onto the same bar and firmed together, and then power applied to the inner of such nuts in an opposite direction will cause the rotation of the bar. The flat unthreaded sides Ill-Ill of the bar materially assists in both the clearing of the threads 9-9 and the threads upon the interior of the nut and a wrench may be employed in co-operation with the flat faces Iii-40 of the bar in assemblying it with the central bars 5.

When the bar is rotated to withdraw it from the green masonry the interruption of the threads 9-9 by the flat sides Iii-ll! causes the threaded part of the bar to function much as a tap so that great force may be developed in removing the clamp from the masonry without endangering the integrity of the green masonry structure which has not completely hardened.

Having described my invention what I claim as new and desire to secure by Letters Patent is:

A clamp, the opposite ends whereof comprise bars of rectangular section having threads formed on a pair of their opposite faces with the faces between said threaded faces left plain, said threads having their tops and sides curved in addition to their spiral curvature, and nuts interiorly threaded to co-operate with the threads on the opposite faces of said bars.

GEO. B. BOSCO. 

